The present invention is directed to a device for piling up flat pieces, for instance printed and folded box blanks, with a device for transferring the boxes beneath a pile of box blanks already formed in a piling station, which station is provided at least with a front stop and a blank jogging device, an arrangement for supporting the front and rear parts of the pile of blanks that has been formed, and an arrangement for supporting the front and rear part of the box blank being introduced beneath the pile.
Devices of this type are generally used in machines for cutting corrugated box board and are usually located toward the end station just before a bundling station. Among these devices, some are known as system pilings from underneath, because all subsequently folded and printed box blanks are inserted underneath the pack being formed. The upper part of the pack is then regularly forwarded to the bundling station.
French Pat. No. 2 087 732 describes the elements composing a piling device which has the purpose to reduce the friction between the lowest box blank of a pile of blanks and the next box blank being inserted underneath the pile and to reduce the friction between the conveying means and the box blank that is being carried into the piling station. For this purpose, a conveying device shifts the front part of the box blank against the stop, the device operates jointly with rollers situated between its belts in the front area of the box blank to be piled up, as well as with a mechanism consisting of several elements moving with a relative motion in order to support the rear part of the pack and to enable the introduction of the next box blank underneath the pack. The next box blank is then supported by these elements. Such a device has, however, important drawbacks because when all the boxes are piled up, the friction acting on the rollers in the front area of the blanks is only a residual and whereas when a new box blank is introduced underneath the pile, its upper face is rubbed over quite a distance against the lower face of the lowermost blank already in the pack or pile. This rubbing distance is equal to the distance between the rollers and the front stop. This friction may damage the printing on the box blank faces and also has a bad effect on the box blank itself. For example, the friction may jeopardize the adherence of various box panels. In fact, the latter have, at this stage of the operation on the blanks, just been glued and folded and, thus, the friction creates the risk that the glued portions will become detached because of the shearing motion and render these panels unable to stick together any longer. Moveover, the piling of boxes or blanks with irregular cut edges on the panels or with handling and air holes might be subjected to jamming if the boxes are placed in an overlapping arrangement.